Ask Pike Insurances, Dublin, I'm not sure if they can help but they have some experience at least with craft type public/product liability and also have sorted house insurance while producing same at home for me, haven't needed a van insurance though but they are worth a try!
You might need to pick a new designation of occupation as it's quite limited I found under the list insurance companies use, I actually managed to get a new designation added through one company I was with initially.